crank no fire!

[tonykgs2000]

Hi all,

I just bought my first 911, a 1985 Carrera. I had a little work done by a local Porsche mechanic and picked up the car today. In addition to other minor work, the fuses were all changed. After driving the car home (it started fine at the mechanic's), I tried this evening to drive it. The engine cranked but won't fire. Unfortunately, I've parked the car in my garage underground, which I doubt a tow truck will fit in. Do I even want AAA to come for this kind of problem? Any recommendations? Many thanks.

[Lupin..the..3rd]

Where are you located? "Metro DC" really doesn't tell us a whole lot.

[tonykgs2000]

i'm near dupont and logan circle

[Jazzbass]

Try a new DME relay. It's located under your driver's seat. The DME relay is a know failure point on these cars - it controls the fuel pump and the engine management system. If it's bad, no fuel and no spark.

If it starts tomorrow, there's a good chance that's the problem. The relay heats up and fails, cools down and works again. I have a spare you could borrow to test, but you'd have to go to Germantown to get it.

Order another one even if the one you have is fine. It's good to have a spare.

[tonykgs2000]

Chris,

thanks for the kind offer and very helpful info, thank you. from the pelican parts website i see "911-618-154-00-M252" at $30.50. is this the part you're speaking of? do i need to order any other parts along with it, according to this diagram:

http://www.pelicanparts.com/cgi-bin/PartsLookup/search.cgi?command=show_page&Catalog_Name=911_USA_84_86_KATALOG&Illustration=901-03&Line_Item=2

[Jazzbass]

That's it.

BTW, if you can solder, you can fix yours (if that is the problem): http://dorkiphus.net/porsche/showthread.php?t=12684

[Dr K]

If it isn't the DME relay (which I agree is the mostly likely failure point on a Carrera), consider the flywheel sensors. If the mechanic's actions led to a larger-than-spec gap, that could keep the engine from firing. Ask me (or just about anyone on this board) how I know...

From whom did you buy the car? Was it local? Go to the threat "Introdouche Yourself" and post photos. We're pretty informal, and most of us (except the a$$#oles) post our first names or nicknames. I'm guessing yours is "Tony." Tell us a little more about yourself. Do you have DIY experience? Are you ready for Autocross and Drivers Ed?

Peter

[tonykgs2000]

Chris,

I read your fantastic post on DME relay repair. Nice one! I'll ring the mechanic in the AM and see what he has to say.

Is the relay an easy removal? Do I have to remove the driver's seat?

And Peter (not "Pete"), thanks to you too. I've now added a signature - oooooohhh! I've been on 2 wheels for 10 years and finally relented. I knew I was not going to own anything with no personality. I had that role covered myself already! So, this is my first 911 and I bought it off a guy near Philly who said he was active in PCA.

I'm not great on DIY - at least not on cars. My BMW bike never needs a THING done to it, so I didn't get too many chances to hone my skills there.

I am ready for Autocross and Driver's Ed. And, I already went to my first PCA auto show out in Virginia last weekend. It was a blast. Some absolute beauties there.

Tony

[tonykgs2000]

oops. forgot to post pics!

[Jazzbass]

Is the relay an easy removal? Do I have to remove the driver's seat?
Removal isn't too bad and can be done w/ the seat in. The relay is bolted to the floor w/ an M6 bolt. Use a 10mm socket to remove and pull out from under the seat. Unplug, plug new relay in, reattach to the floor.

Nice car. Obviously, since you bought an 85, you have both taste and class.

[KevinOyler]

Tony,

Agree the car looks nice. I would suggest you check and reinstall your fuses before you do much else. It's unusual to replace all the fuses. May indicate a problem there?

[ludwig]

Over the summer I had ASG do a major service on my new to me '85 911. Car finished, they came and picked me up at the metro. Went back to ASG, parked, paid, and left. I stopped at 7/11 about 5 minutes later. Go to start the car and she would crank but not fire. Imagine my feelings of disbelief. No tach movement. I called ASG. About 10 minutes later, one of their guys (forgot who) pulls up. He swapped a known good DME - still nothing. Then we opened the engine cover and looked around. Up above the engine, to the left of the throttle body are three plastic sensor connections - mine are old and crumbly and had wiggled loose. Plug them back together and the car started and ran just fine.

You might want to check these connections. They are "AMP" style connectors. Found replacements here:

http://eagleday.stores.yahoo.net/ampconnectors.html

Now I just need to buy them and install them.

Good luck, report back with your findings.

-Chris

[Jazzbass]

You might want to check these connections. They are "AMP" style connectors. Found replacements here:

http://eagleday.stores.yahoo.net/ampconnectors.html

You get a whole bunch of win for that link. I've wanted to buy these connectors for a while but never know who the mfr was or what the name of the connector series was. Just so there's no confusion, "AMP" is the manufacturer, "Junior Timer" is the style of connector. Not saying this to be nit-picky; AMP makes hundreds of different kind of connectors. Don't want someone to try to order "AMP" connectors and get the wrong thing.

[ludwig]

took me a long time to find them. I used to drive old Saabs. Engine bays were full of these connectors. They work great until the heat and age makes them brittle and crumbly. Looking forward to being able to do a proper fix instead of the old wire nut crap of yesteryear.

[realroadrage]

You get a whole bunch of win for that link.

x2, I need to replace some of mine that are cracked. Now I just have to see which sizes I need to order.

[Trak Ratt]

You get a whole bunch of win for that link. I've wanted to buy these connectors for a while but never know who the mfr was or what the name of the connector series was. Just so there's no confusion, "AMP" is the manufacturer, "Junior Timer" is the style of connector. Not saying this to be nit-picky; AMP makes hundreds of different kind of connectors. Don't want someone to try to order "AMP" connectors and get the wrong thing.
May need to "sticky" link in Tech area ?

[Jazzbass]

May need to "sticky" link in Tech area ?
I'm going to make a re-wiring post for there. I'll put this link in with the others

[tonykgs2000]

Thank you all for your help on the DME relay. I was pretty dismayed at the car not starting yesterday after handing over several thou to Autobahn Inc. but you all helped me big time!

This morning I rode down to BMW/Porsche of Arlington, picked up a new relay and installed it in 2 minutes. She started right up. The relay was not bolted to the body. Does it need to be?

There's the PCA "Trick or Beep" rally coming up, and some people apparently decorate their cars. I was thinking of making mine look like a trouble-free car!

Thanks again.

Tony

[Trak Ratt]

There's the PCA "Trick or Beep" rally coming up, and some people apparently decorate their cars. I was thinking of making mine look like a trouble-free car!

Thanks again.

Tonygood luck with that!
Glade the relay worked out.

[paul]

I hope you kind gents can give me a hand with a similar problem as Tony..

I believe this is my first post and I should post a picture and I will (promise) once I get this problem fixed. The patient is a 87 911.

I was driving down Ritchie Highway in Severna Park (MD) when the engine just died. There were lights etc and I could crank but no start. So, I coasted to the shoulder. I tried again - cranks fine and I can even smell some fuel ( I think maybe not since I was standing by the road during rush hour) but no start. My first thought was the DME relay and I have one but it is at home sitting on a shelf in the garage. I had the car flatbeded home. BTW a nice white 911 Targa honked. If one of you was it - I appreciate it :)

Anyway - I swapped out the DME relay and still no start. The gas gauge was low and thinking the gauge was maybe faulty, I dumped in more gas - still no start. The engine cranks good so far. I did some troubleshooting (w/ Benthley's help) the DME relay harness and it checks out (voltages across the pins etc). I tried to listen for the fuel pump but with the muffler racket - I couldn't tell. I will get the front up on jacks and try to listen while I get somebody to crank it.

I also checked the three sensors/plugs in the engine bay (on the left) and they look fine (i.e. not obviously broken). I checked the battery and the voltage is 14V+ so I don't think it's the battery or alternator.

Right now, I'm thinking fuel pump. Is there an easier way to test for the fuel pump without getting under the car? I checked the fuse and it's fine.

So, what else should I check??

Paul

[Racer29]

.. I had a similar problem with my 87. There are two sensors at the flywheel. Same part number. TDC and engine speed RPM. One sends a signal to the fuel pump to pump fuel.
Easy replacement through the left rear fender well. If you don't move the holding bracket it is a drop in replacement.Worked for me...good luck I hope this helps

[paul]

Thanks Kevin - I will put those items on my things-to-check list.

The next thing I plan on doing is to check for spark since that is pretty fundamental. Don't know why I didn't think of it earlier when there was plenty of daylight left .. :bang:

[Dr K]

Don't know why I didn't think of it earlier when there was plenty of daylight left .. Ahhh, but it's easier to see in the dark.

Peter

[Jazzbass]

Easiest way to test the fuel pump is to put a fuel pressure gauge on the left side FI rail on the engine. This will tell you if the pump is working and that it's putting out enough pressure (> 3bar IIRC). If the pump isn't working it could be:

1. Bad pump
2. Bad DME relay
3. Bad DME
4. Bad sensors as Dave indicated

The DME will only turn on the fuel pump when the ignition is on AND either (a) you're cranking the starter or (b) the engine speed > 400 rpm.

If you don't have a fuel pressure gauge, listen for the pump whine when someone is cranking the engine. Alternatively, jumper the fuel pump on using a jumper wire to the bottom of Fuse 2 and Fuse 3 (fuel pump fuse). That'll turn the pump on regardless of the DME or relay. That can help you figure out if it's the pump or the DME.

Make sure all the connectors in the engine bay are good and closed. As discussed earlier in this thread, these connectors like to deteriorate over time. If the speed or the ref sensors (left side of the engine, bolted to the manifold) are undone, that's a problem. Likewise any of the connectors on the main FI parts - throttle body, etc. Sounds like you're good with a meter; almost all of these sensors can be tested. Make sure:

- Throttle position reads fine
- AFM is fine
- Speed sensor resistance is in range
- Position sensor is in range
- Cylinder Head Temp is in range (this is a likely culprit, BTW, esp if you still have the old 1 wire sensor)

I like to test the sensors at the DME connector itself to make sure the entire circuit is functional. BTW, was the spare DME relay you put in new or used?

- Bad coil - test resistance.

My guess? One of these:
- bad fuel pump
- CHT sensor

FWIW, although it wouldn't have helped in this case, hopefully you can see why having a spare DME relay IN THE CAR is a good idea. Nothing worse than paying $$$$ to have your car towed just so you can install your spare $30 relay.

[tdatk]

Easiest way to test the fuel pump is to put a fuel pressure gauge on the left side FI rail on the engine. This will tell you if the pump is working and that it's putting out enough pressure (> 3bar IIRC). If the pump isn't working it could be:

1. Bad pump
2. Bad DME relay
3. Bad DME
4. Bad sensors as Dave indicated

The DME will only turn on the fuel pump when the ignition is on AND either (a) you're cranking the starter or (b) the engine speed > 400 rpm.

If you don't have a fuel pressure gauge, listen for the pump whine when someone is cranking the engine. Alternatively, jumper the fuel pump on using a jumper wire to the bottom of Fuse 2 and Fuse 3 (fuel pump fuse). That'll turn the pump on regardless of the DME or relay. That can help you figure out if it's the pump or the DME.

Make sure all the connectors in the engine bay are good and closed. As discussed earlier in this thread, these connectors like to deteriorate over time. If the speed or the ref sensors (left side of the engine, bolted to the manifold) are undone, that's a problem. Likewise any of the connectors on the main FI parts - throttle body, etc. Sounds like you're good with a meter; almost all of these sensors can be tested. Make sure:

- Throttle position reads fine
- AFM is fine
- Speed sensor resistance is in range
- Position sensor is in range
- Cylinder Head Temp is in range (this is a likely culprit, BTW, esp if you still have the old 1 wire sensor)

I like to test the sensors at the DME connector itself to make sure the entire circuit is functional. BTW, was the spare DME relay you put in new or used?

- Bad coil - test resistance.

My guess? One of these:
- bad fuel pump
- CHT sensor

FWIW, although it wouldn't have helped in this case, hopefully you can see why having a spare DME relay IN THE CAR is a good idea. Nothing worse than paying $$$$ to have your car towed just so you can install your spare $30 relay.

As usual excellent tech reply Chris ;)

[paul]

OK

Tested for spark - used extra plug as well as one of the AutoZone spark tester - we got spark.
Definitely smell of gas from muffler outlet - but does this mean pump is working? If not, I will jumper the pump and listen for it and also check cap/rotor etc. when I get back from work tomorrow.

Thanks for all of the tips/suggestions.

btw - the spare DME relay is brand new from Pelican

[paul]

Jumpered the fuel pump via fuse panel (battery hot to fuse #6 bottom). Expected a mechanical whirring sound - instead just got a thud. Appears to be a bad pump. I thought there was the gas smell last night but must have been residue. From checking other posts, the odor is obvious.

So, is it unanimous that the culprit is the fuel pump??

[BlackTalon]

So, is it unanimous that the culprit is the fuel pump??YES!!!!

But then again, I have no clue when it comes to this kind of stuff... :lol:

[paul]

OK - I got 1 vote for a definite YES! :)

I actually wanted to jack the car and really confirm with my head/ears right next to it....maybe the pump is really quiet..

[Rick V]

I have a spare (used but good) fuel pump from an 88 if you want it. I might be in the NOVA area on Sat.

[Jazzbass]

..maybe the pump is really quiet..

In my experience they are not. My first one was loud as hell. I just put a new one in the car in July and while it was quieter, you definitely could here it when it was on.

Before changing pumps, though, I'd do a confirmation test. The best test is to make sure you have pressure (2.5 bar) at the fuel rails via the test port shown here:

8819

If you don't have a fuel pressure gauge, a true Dorki style ghetto test would be to remove the test port cap, hold a cup under it and have a helper jumper the fuse. If the pump works, you should see fuel flow. If not, you get nothing. If you do this, obviously be careful with the gasoline but also make sure not to lose the little ball bearing that's inside the test port cap.

[paul]

Rick V - you got pm

[Rick V]

In my experience they are not. My first one was loud as hell. I just put a new one in the car in July and while it was quieter, you definitely could here it when it was on.

Before changing pumps, though, I'd do a confirmation test. The best test is to make sure you have pressure (2.5 bar) at the fuel rails via the test port shown here:

8819

If you don't have a fuel pressure gauge, a true Dorki style ghetto test would be to remove the test port cap, hold a cup under it and have a helper jumper the fuse. If the pump works, you should see fuel flow. If not, you get nothing. If you do this, obviously be careful with the gasoline but also make sure not to lose the little ball bearing that's inside the test port cap.
Make damn sure you have the cover over the fuse panel right there as well.:roll:

[Jazzbass]

Make damn sure you have the cover over the fuse panel right there as well.:roll:
Pussy :lol:

Good point. Forgot about that - my rear fuse panel is long gone.

[paul]

Rick has graciously offered a pump gratis - all the help and now this...

Thank you to all :D

[Rick V]

Yeah-Yeah, now that I have done a good dead I can get back to being my typical asshat self.

[tonykgs2000]

Friends,

A few weeks ago I posted the "crank no fire" thread here, and swapped out the DME relay. She started right up! Then I went out of town for a week (had to miss the tech inspection at ASG), went to my garage tonight and...crank - no fire! If anyone has a moment to swing by and take a look, I would be most grateful.

Thanks.